Immunoprecipitation of phosphorylated p70 S6 Kinase from 293 cell extracts (cells were serum-stimulated as indicated) under nondenaturing or denaturing conditions, followed by Western blot analysis, using Phospho-p70 S6 Kinase (Thr421/Ser424) Antibody.

After the primary antibody is bound to the target protein, a complex with HRP-linked secondary antibody is formed. The LumiGLO® is added and emits light during enzyme catalyzed decomposition.

Western blot analysis of Non-phosphorylated p70 MCF7 Control Cell Extracts (-) and Phosphorylated p70 MCF7 Control Cell Extracts (+), using the indicated antibodies.

Immunoprecipitation of phosphorylated p70 S6 Kinase from 293 cell extracts (cells were serum-stimulated as indicated) under nondenaturing or denaturing conditions, followed by Western blot analysis, using Phospho-p70 S6 Kinase (Thr421/Ser424) Antibody.

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Thr421/Ser424 of human p70 S6 kinase. Monoclonal antibody is produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Thr389 of human p70 S6 Kinase, or corresponding to the sequence of human p70 S6 kinase. Antibodies are purified by Protein A and peptide affinity chromatography.

Background

p70 S6 kinase is a mitogen activated Ser/Thr protein kinase that is required for cell growth and G1 cell cycle progression (1,2). p70 S6 kinase phosphorylates the S6 protein of the 40S ribosomal subunit and is involved in translational control of 5' oligopyrimidine tract mRNAs (1). A second isoform, p85 S6 kinase, is derived from the same gene and is identical to p70 S6 kinase except for 23 extra residues at the amino terminus, which encode a nuclear localizing signal (1). Both isoforms lie on a mitogen activated signaling pathway downstream of phosphoinositide-3 kinase (PI-3K) and the target of rapamycin, FRAP/mTOR, a pathway distinct from the Ras/MAP kinase cascade (1). The activity of p70 S6 kinase is controlled by multiple phosphorylation events located within the catalytic, linker and pseudosubstrate domains (1). Phosphorylation of Thr229 in the catalytic domain and Thr389 in the linker domain are most critical for kinase function (1). Phosphorylation of Thr389, however, most closely correlates with p70 kinase activity in vivo (3). Prior phosphorylation of Thr389 is required for the action of phosphoinositide 3-dependent protein kinase 1 (PDK1) on Thr229 (4,5). Phosphorylation of this site is stimulated by growth factors such as insulin, EGF and FGF, as well as by serum and some G-protein-coupled receptor ligands, and is blocked by wortmannin, LY294002 (PI-3K inhibitor) and rapamycin (FRAP/mTOR inhibitor) (1,6,7). Ser411, Thr421 and Ser424 lie within a Ser-Pro-rich region located in the pseudosubstrate region (1). Phosphorylation at these sites is thought to activate p70 S6 kinase via relief of pseudosubstrate suppression (1,2). Another LY294002 and rapamycin sensitive phosphorylation site, Ser371, is an in vitro substrate for mTOR and correlates well with the activity of a partially rapamycin resistant mutant p70 S6 kinase (8).

Data Sheets & Documentation

For Research Use Only. Not For Use In Diagnostic Procedures.
Cell Signaling Technology is a trademark of Cell Signaling Technology, Inc.
PhosphoPlus is a trademark of Cell Signaling Technology, Inc.
LumiGLO is a registered trademark of Kirkegaard & Perry Laboratories.
U.S. Patent No. 5,675,063.